This invention relates to a conveyor belt scraper.
U.S. Pat. No. 6,076,656 describes a conveyor belt scraper which includes a segmented scraper blade composed of blade segments arranged side by side on blade segment supports each of which includes a parallelogram linkage. A gas inflated biasing means, typically an inflatable tube or hose, extends through the linkages and is inflated to cause the linkages to displace the blade segments towards the belt surface. The individual mounting of the blade segments enables them to wear at different rates, to take account of different belt loading conditions across the width of the belt, while still maintaining an effective scraping action.
Conveyor belt scrapers according to U.S. Pat. No. 6,076,656 are marketed under the trade marks DIRTWHACKER® and SCAVENGER®. These scrapers include, for each parallelogram linkage, a flexible curtain which hangs over the linkage and prevents material which is scraped off the conveyor belt from falling directly onto the linkage. This reduces the risk of the falling material fouling and jamming the linkage. There is also a rigid plastics deflector extending over the curtain on one side of the linkage to deflect material away from the linkage and curtain to provide further protection to the linkage and also to prevent material from falling directly onto the curtain and causing premature damage to it.
The known scrapers as described above work well in practice. Problems have however been encountered in situations where the conveyor belt runs “dry”, i.e. there is no conveyed material on the belt.
Frictional contact between the scraper and the belt generates substantial heat. In the conventional, practical arrangement the deflector and curtain, which is typically made of natural rubber, are clamped between the blade segment and a bracket formation on the linkage. The deflector and curtain accordingly act as thermal insulators between these components. When there is material on the belt which is scraped off by the scraper at least some of the thermally generated heat is conveyed away from the assembly by the material itself. However when the belt runs “dry”, there is no such removal of heat and excessive heat can build up in the assembly, possibly leading to heat deterioration of the curtain and deformation or even melting of the plastics deflector. This in turn can lead to a loosening of the connection between the bracket and the linkage. The loosened bracket, i.e. blade segment, can then vibrate or chatter against the belt, resulting in further build-up of heat and rapid wear to the blade and also to the other mechanical components.
A solution to this particular problem would be to avoid running the belt “dry”. However many handling plants have control systems and protocols which automatically run conveyor belts even when there is no material to convey.
Rapid wear of the scraper apparatus can also take place in situations where particularly abrasive particulate material is transported by the conveyor belt. It has been observed that the deflector itself can undergo rapid wear as a result of the material falling onto it. It is believed that such wear is mainly attributable to the fact that the deflector is oriented at a relatively acute angle relative to the horizontal and so is largely exposed to vertically falling material which rapidly abrades it. If the deflector and curtain are worn through, the mechanical linkage itself will be exposed directly to the falling material scraped off the belt, and this may have the effect of shortening the life of the scraper.
The present invention seeks to provide, in a conveyor belt scraper of the type here in question, features which can contribute to reducing the rate of wear of the scraper apparatus.